Drug & supplement interaction

Eurycoma Longifolia + Clemastine

Clemastine brand name: Tavist Allergy.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Eurycoma Longifolia and Clemastine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Eurycoma Longifolia and Clemastine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Clemastine and Eurycoma Longifolia in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Eurycoma Longifolia safety at a glance

Eurycoma Longifoli... overall Use caution Generally tolerated short-term in studies, but long-term safety and product quality are uncertain.
Pregnancy Avoid Not enough safety data and possible hormonal effects, so avoid during pregnancy.
Breastfeeding Avoid No reliable safety information, so it is best to avoid while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Pharmacist analysis

Although there is no known interaction in this case, Eurycoma longifolia, most commonly known as Tongkat Ali, does have some potential interactions that are important to be aware of.

For example, it may interact with the following:

  • CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES
  • CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES
  • CYTOCHROME P450 2A6 (CYP2A6) SUBSTRATES
  • Propranolol
  • Testosterone

Tongkat Ali has been reported to inhibit certain metabolizing enzymes in the liver (the ones mentioned above) and therefore, may increase the levels of substances metabolized by those enzymes. This could potentially affect the way these substances work or how long they stay in your system.

In regard to propranolol, some studies show that Tongkat Ali decreases how well propranolol is absorbed in the gut and could reduce its effects. It is not known if separating administration will prevent this interaction/

Lastly, testosterone, Tongkat Ali may theoretically further increase levels of testosterone, a hormone responsible for various functions in the body. You should be cautious combining the two.

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Still wondering about combining Clemastine and Eurycoma Longifolia? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Clemastine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Clemastine is filed under 4 classifications — including anticholinergic drugs, photosensitizing drugs, seizure threshold lowering drugs. Eurycoma Longifolia has documented interactions with 5 drug classes — the most serious being propranolol (inderal) (moderate), cytochrome p450 1a2 (cyp1a2) substrates (minor) and cytochrome p450 2a6 (cyp2a6) substrates (minor) — and none of Clemastine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Eurycoma Longifolia Does Interact With Other Medications

Eurycoma Longifolia has 3 moderate, 245 minor known drug interactions in our database — Clemastine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 3 Minor 245 No known interaction 2,582 (incl. Clemastine)
Taking anything else?

Check Another of Your Medications Against Eurycoma Longifolia

Covers the 2,830 medications we’ve checked against Eurycoma Longifolia. Pick one to open its full report.

What to actually watch for

What Eurycoma Longifolia Itself Has Been Linked To

This is not an interaction — nothing below involves Clemastine. It is the side-effect record for Eurycoma Longifolia on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Eurycoma Longifolia, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Liver problems Worth acting on Additional detail

    “Some research in both humans and animals suggests that Eurycoma longifolia might increase testosterone levels. If testosterone levels are increased beyond the normal range, there is risk of testosterone-related side effects which could include acne, insulin resistance, hepatotoxicity, and others.”

    Eurycoma Longifolia · Natural Medicines adverse-effect record, reported in acne.

    1 source cited
    1. 17924. Tambi MI, Imran MK, Henkel RR. Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism? Andrologia 2011 Jun 15. doi: 10.1111/j.1439-0272.2011.01168.x. [Epub ahead of pri PubMed
  • Acne Additional detail

    Recorded for Eurycoma Longifolia in the same Natural Medicines adverse-effect record shown under Liver problems above.

Everything above comes from the Natural Medicines adverse-effect record for Eurycoma Longifolia — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Clemastine’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Clemastine column appears here.

From our Q&A

Questions About Eurycoma Longifolia or Clemastine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Eurycoma Longifolia or Clemastine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Clemastine

This page covers Eurycoma Longifolia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Clemastine page lists 72 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), Alfalfa (moderate) and Angel's Trumpet (moderate).

By severity: 3 major · 57 moderate · 12 minor.

From our pharmacist’s overview on the Clemastine page

“Clemastine (Tavist Allergy) is an older, sedating antihistamine that already dries the mouth, blurs vision, and slows the gut, and that is exactly why this list earns real caution rather than a quick skim. Thirty of the 72 supplements on file pile the same drying, sedating anticholinergic load on top, and two of the three major-rated e…”

Reviewed by 2 · Jul 18, 2026

Open the Clemastine interaction page

One more smart check

Taking Eurycoma Longifolia as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,122 real supplement products containing Eurycoma Longifolia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Eurycoma Longifolia. Even though Eurycoma Longifolia itself has no known interaction with Clemastine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Eurycoma Longifolia and Clemastine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Eurycoma Longifolia
Top 10%

#117 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Clemastine
Steady interest

#1,454 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Eurycoma Longifolia reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Eurycoma Longifolia and Clemastine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Eurycoma Longifolia

What is Eurycoma Longifolia?

Eurycoma Longifolia
  • Low testosterone or low libido in men
  • Male fertility support
  • Athletic performance and muscle strength
  • Energy and fatigue
  • Stress and mood
  • General male enhancement

Eurycoma longifolia (tongkat ali) is a Southeast Asian herb most popular for supporting testosterone, libido, and male fertility, with some small human studies suggesting possible benefits. However, the overall evidence is still limited and product quality varies widely, so talk with your pharmacist or doctor before using it, and avoid it if you are pregnant or breastfeeding.

Eurycoma longifolia · Simaroubaceae · Root (and root extracts) · Capsules, tablets, powder, extracts, teas, and blended supplement products

An interaction check asks whether these two react with each other — it does not ask whether Eurycoma Longifolia is a good idea for someone in your situation. Here is what our Eurycoma Longifolia record says about it on its own.

Eurycoma Longifolia: dosing

There is no official or universally agreed-upon dose for Eurycoma longifolia. Studies have used different standardized extracts at different strengths, which makes it hard to recommend one specific amount.The best approach is to follow the directions on the product label and not exceed them.

From our Eurycoma Longifolia monograph — the full record covers uses, side effects and every documented interaction.

Read the full Eurycoma Longifolia monograph & all interactions
Medication

About Clemastine

What Is Clemastine Used For?

Brand name: Tavist Allergy

Clemastine treats symptoms of allergic rhinitis (hay fever and similar nasal allergies) — including sneezing, runny nose, itching, and watery eyes. The oral solution (Clemastine Fumarate syrup) is indicated for adults and children aged 6 through 12 years. The tablets (Clemastine Fumarate and Clemsza) are indicated for adults.

Clemastine also treats mild, uncomplicated allergic skin reactions — specifically urticaria (hives) and angioedema (swelling under the skin) — at the appropriate dosage level, in both the oral solution and tablet forms.

See full Clemastine drug information
Keep checking

Other Drugs & Eurycoma Longifolia

Browse every other medication we’ve checked against Eurycoma Longifolia — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
3Moderate
245Minor
2,581No known interaction
3 Moderate 245 Minor 2,581 No interaction
Moderate

3 interactions

Minor

245 interactions

Showing 60 of 245 minor interactions — see all 245 on the Eurycoma Longifolia page.

No interaction 2,581 drugs checked — show the list

We also checked Eurycoma Longifolia against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,581 medications checked with no known interaction — see the full Eurycoma Longifolia list.

See the full Eurycoma Longifolia interactions page
See every supplement checked against Clemastine, ranked by severity
Evidence & sources

Eurycoma Longifolia References

The 4 references that drive our Eurycoma Longifolia monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Salman SA, Amrah S, Wahab MS, et al. Modification of propranolol's bioavailability by Eurycoma longifolia water-based extract. J Clin Pharm Ther 2010;35:691-6. PubMed
  2. Tambi MI, Imran MK, Henkel RR. Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism? Andrologia 2011 Jun 15. doi: 10.1111/j.1439-0272.2011.01168.x. [Epub ahead of pri PubMed
  3. Han YM, Kim IS, Rehman SU, Choe K, Yoo HH. In vitro evaluation of the effects of Eurycoma longifolia extract on CYP-mediated drug metabolism. Evid Based Complement Alternat Med 2015;2015:631329.
  4. Chinnappan SM, George A, Pandey P, Narke G, Choudhary YK. Effect of Eurycoma longifolia standardised aqueous root extract-Physta ® on testosterone levels and quality of life in ageing male subjects: a randomised, double-blind, placebo-controlled multicent

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Eurycoma Longifolia and Clemastine Together: Common Questions

Is it safe to take Eurycoma Longifolia with Clemastine?
We do not list a known interaction between Eurycoma Longifolia and Clemastine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Eurycoma Longifolia and Clemastine combination checked?
Interactions in our licensed database are recorded against drug classes. Clemastine is filed under 4 classifications, and Eurycoma Longifolia has documented interactions with 5 drug classes — none of Clemastine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Eurycoma Longifolia interact with any other medications?
Yes. Eurycoma Longifolia has 248 documented drug interactions in our database — Clemastine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Clemastine interact with any supplements?
Yes. Clemastine has documented interactions with 72 supplements in our database — Eurycoma Longifolia is not one of them. The Clemastine interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Eurycoma Longifolia monograph Uses, safety profile, and every drug interaction in one place Clemastine drug information The full plain-English guide to this medication Clemastine supplement interactions Every supplement checked against Clemastine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Clemastine and Eurycoma Longifolia?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.